Burner apparatus for forming a finish on a glass container

ABSTRACT

A burner apparatus for forming a finish on a hollow glass article on a production line, such as a glass container. Glass containers having an integrally formed moil portion on the upper end of the container body portion are loaded in sequence on a continuously moving endless conveyor which carries the containers in line through a heating zone. During their transit through the heating zone, the containers pass between a linear row of opposed burners which direct a high intensity row of flame jets accurately against a narrow portion of the container body to first thermally sever the moil portion from the body and to subsequently form a beaded finish on the container. The containers are rotated during their passage through this set of burners at a controlled rate to achieve the desired finish formation. The burner assembly includes top and bottom housings and an intermediate shim plate that define together plural slots connected to a fuel chamber that is in a recess longitudinally of the burner housing. Air and fuel are supplied to the recess chamber for combustion upon exit from said slots.

United States Patent n91 Banyas et al.

[451' Feb. 5, 1974 BURNER APPARATUS FOR FORMING A FINISH ON A GLASSCONTAINER [75] Inventors: John D. Banyas, Toledo; Edward A.

i Ross, Waterville, both of Ohio [73] Assignee: Owens-Illinois, Inc.,Toledo, Ohio [22] Filed: Aug. 29, 1972 [21] Appl. No.: 284,565

Related US. Application Data [62] Division of Ser. No. 77,425, Oct. 2,1970, Pat. No.

[52] US. Cl 239/418, 239/433, 239/555, 239/568 [51] Int. Cl. F23d 11/10,F23d 13/40, F23d 15/00 [58] Field of Search 239/418, 433, 568, 555

[56] References Cited UNITED STATES PATENTS 2,484,123 10/1949 Scherlm,239/555 1,888,791 ll/l932 Cole 239/418 1,373,565 4/1921 Kunitz 239/4183,503,557 3/1970 Hutton, .lr 239/433 3,477,646 l1/l969 Lytle.... 239/4332,149,526 3/1939 Johnson 239/418 2,407,370 9/1946 llughey 239/4183,615,054 10/1971 Botz 239/568 Primary ExaminerLloyd L. King Attorney,Agent, or Firm-.1. R. Nelson et al.

[5 7] ABSTRACT A burner apparatus for forming a finish on a hollow glassarticle on a production line, such as a glass container. Glasscontainers having an integrally formed moil portion on the upper end ofthe container body portion are loaded in sequence on a continuouslymoving endless conveyor which carries the containers in line through aheating zone. During their transit through the heating zone, thecontainers pass between a linear row of opposed burners which direct ahigh intensity row of flame jets accurately against a narrow portion ofthe container body to first thermally sever the moil portion from thebody and to subsequently form a beaded finish on the container. Thecontainers are rotated during their passage through this set of burnersat a controlled rate to achieve the desired finish formation. The burnerassembly includes top and bottom housings and an intermediate shim platethat define together plural slots connected to a fuel chamber that is ina recess longitudinally of the burner housing. Air and fuel are suppliedto the recess chamf ber for combustion upon exit from said slots.

@ sea i 2 Claims, 8 Drawing Figures PAIENIED FEB 51974 SHEEI 5 OF 6PAIENIED 51974 SHEET 6 0F 6 BURNER APPARATUS FOR FORMING A FINISH ON AGLASS CONTAINER RELATED PATENTS AND APPLICATIONS This application is adivisional of our copending parent application Ser. No. 77,425, filedOct. 2,1970, now US. Pat. No. 3,726,559.

The machine disclosed in this application forms a portion of the overallcontainer production line disclosed and claimed in the commonly ownedcopending application of Richard A. Heaton, et al., Ser. No.

BACKGROUND OF THE INVENTION As explained in detail in the aforementionedHeaton et al. US. Pat. No. 3,703,363, the glass container of Heaton US.Pat. No. 3,372,826 is initially formed in a ribbon-type forming machinewith a moil or waste portion formed integrally with the container bodyand projecting upwardly from the container body. The purpose of theintegrally formed moil is to enable the freshly formed container to behandled immediately upon its removal from the forming machine, at a timewhen the temperature of the freshly formed container is so high thatmechanical handling elements may mar or deform those portions of thecontainer with which they come in contact. The transfer machine of theaforementioned Banyas US. Pat. No. 3,590,982 is designed to take thefreshly formed containers from the ribbon machine by grasping the moilportion ,of the freshly formed containers, thus avoiding contact withthat portion of the article which will form the ultimate finishedcontainer.

The function of the present'machine and methodis to receive thecontainers with the integrally formed moil from the transfer machine ofBanyas US. Pat. No. 3,590,982, to sever the moil portion and to form thecontainer finish after the moil has been severed. The

present invention is especially concerned with the structure of theburners employed in the moil severing and finish forming steps.

SUMMARY OF THE INVENTION The burner apparatus of the present inventionis utilized' in a machine that takes the form of an endless chainconveyor driven in continuous movement along an endless path andcarrying a series of uniformly spaced container chuck assemblies.

Containers with integrally formed moil portions are loaded onto theindividual chucks in an upright position at a loading point on thehorizontal upper run of the endless conveyor. Each chuck includes asprocket which is engageable with various chains mounted along selectedportions of the chuck path to drive the chuck in rotation as it passesalong the chain. After the containers are loaded onto the chucks, theypass along the upper run of the conveyor between a pair of op- 2 posedpre-heat burners which extend along opposite sides of the path ofmovement of the containers. The pre-heat'burners extend along the upperrun of the conveyor and around the first end turn section and functionto maintain the temperature of the container within a predeterminedrange during its passage of this portion of their path. A stationarychain engages the chuck sprockets on the upper run to drive the chucksand supported containers in continued rotation to achieve an evenexposure of the containers to the pre-heat burners.

After the containers pass around the end turnsection, they are invertedand move into a main burner section which includes opposed burners ofnovel construction extending along the lower run of the conveyor atopposite sides of the path of movement of the containers. The mainburners produce a linear row of narrow flame jets which are directedaccurately to a narrow band on the containers at the, juncture of themoil portion and container body portion. During their passage throughthe main burners, the chuck sprockets are engaged by one run of anendless chain which is driven by a reversible variable speed drive in adirection and speed such that a selected rate of rotation of thecontainers is maintained during their passage through the main burners.During their transit through the first section of the main burners, themoil portion is thermally severed by the action of the flame jets anddrops freelyfrom the container body. A beaded finish is formed on thesevered edge as the containers pass through the remaining section of theburners. The burners are constructed from individual burner. sections,so that different fuels, fuel pressures, .flame widths, etc. may beemployed at different sections of theburner. The burner sections aremounted for adjustment vertically relative to the container path,horizontally toward and away from the container path and also pivotallyabout a horizontal axis parallel to the container path so that the angleof impingement of the flame jets on the containers can be regulated.

Although the machine and method are specifically described in terms ofhandling a specific glass container, the invention is equally capable ofhandling other types of glass containers or hollow glass articlesinitially formed. as a blank with an integral moil, such as electriclight bulb envelopes or glass tumblers, for example.

Other objects, features and advantages of the invention will becomeapparent in the following specification and in the drawings.

IN THE DRAWINGS FIG. 1 is a very schematic side elevational diagram of aburn-off machine embodying the present invention;

FIG. 2 is a partial side detail view of the finish end portion of acontainer blank as received by the burn-off machine;

FIG. 3 is a detail side elevational view of the finish portion of thecontainer after the finish has been formed by the burn-off machine;

FIG. 4 is a perspective view of a portion of a main burner module,partially in cross-section;

FIG. 5 is a detail plan view showing a portion of a burner shim;

FIG. 6 is a detail cross-sectional view, taken in a vertical plane,through the main burner;

FIG. 7 is a top plan view of a portion of the main burner assembly; andA FIG. 8 is a detail cross-sectional view of the burner assembly showingthe mechanism for pivotally adjusting the burners.

GENERAL DESCRIPTION The function of the burn-off machine of FIG. 1 is toreceive containers C (FIGS. 2 and 3) having an integral moil or wasteportion M projecting upwardly from the container finish, to burn off themoil M and form a beaded finish FIN (FIG. 3) on the container, and tosubsequently deposit the container into a pocket conveyor. 1

The burn-off machine forms a part of the overall container productionline which is the subject matter of U. S. Pat. No. 3,703,363. In thisparticular production line, the bulb-shaped containers are formed on aribbon machine with an integral moil portion projecting upwardly fromthe container mouth or finish. The containers are severed from theribbon on the ribbon machine at the top of this moil portion and themoil portion is simultaneously grasped by a finger assembly on atransfer machine which forms the subject matter of U.S. Pat. No.3,590,982. The finger assembly of the transfer machine is adapted tograsp the freshly formed container by the moil portion, because at thetime the container is engaged by the transfer machine, it is still at arelatively high temperature from the forming operation and susceptibleto being marred or deformed by the finger assemblies of the transfermachine. To complete the container, it is necessary that the moilportion be subsequently severed from the container and that a beadedfinish be formed at the point of severance.

In FIG. 1, an extremely schematic diagram of the burn-off machine ispresented for the purpose of affording an overall view of the machineand the relationship of the individual mechanisms and components to eachother. The various components and mechanisms will be individuallydescribed in detail below, their relative sizes and locations being suchthat it is not possible to show details of all mechanisms in a singleview.

Referring to FIG. 1, the burn-off machine takes the form of an endlesschain conveyor, the chain of which is schematically illustrated at 40. Aseries of uniformly spaced container chucks 42 are mounted upon andcarried by the chain in continuous movement along an endless path havinghorizontally extending upper and lower runs 43 and 44 respectively.Chain 40 is supported and guided in movement along its endless path bychain tracks mounted upon the machine frame F, now shown in FIG. 1, butdescribed in greater detail below. Chain 40 is driven along its endlesspath in a counterclockwise direction as viewed in FIG. I by a main drivesprocket 46 driven in in turn by a main drive motor 48, and also by aslave drive sprocket 50 which is drivingly coupled through a slip clutch52 to a slave drive motor 54.

Main drive sprocket 46 is meshed with both the upper and lower runofchain 40 at points P-1 and P-2 and supplies the major portion of thedriving force for chain 40. The the remaining minor portion of thenecessary driving force is supplied by slave drive sprocket 50 which ismeshed with the lower run of chain 40 at point P-3 and driven by itsdrive motor 54 through slip clutch 52. Motor 54 is driven at a rate suchthat slave drive sprocket 50 attempts to move chain 40 at a faster speedthan chain 40 is driven by main drive sprocket 46, part of the excesspower being applied to tension chain 40 and the remainder absorbed inslip clutch 52. The purpose of slave drive sprocket 50, in addition tothat of supplying a ,portion of the motive power to cahin 40 is tomaintain a constant tension in that portion of chain 40 on lower run 44between points P-2 and P-3. By employing two drives, the magnitude ofthe chain tension is reduced there are two drives each effectivelypulling a short length of chain rather than a single drive pulling onelong length of chain.

Overall tensioning of the chain is accomplished by mounting main drivesprocket 46 and that portion of the chain track defining the left-handend turn 56 of the chain path upon a sub-frame 58 which is mounted forsliding movement from right to left and vice versa as viewed in FIGS. 1and 4 upon the fixed frame F, of the burn-off machine. Sub-frame 58 canbe shifted horizontally as viewed in FIG. 1 relative to the fixed frameas by a screw jack mechanism schematically illustrated at 60 toestablish overall chain tension. Adjustment of sub-frame 58 relative tothe fixed frame by the jack mechanism 60 "establishes the tension of themajor portions of the horizontal upper and lower runs 43 and 44 of chain40 i.e., that portion of the chains to the right of the points P-2 andP-3 enmeshed with sprocket 46. While it is desired to have an adequateamount'of tension in the horizontal runs of the chain, it is desired tohave the chain somewhat looser in its passage around end turn 56 andthus end turn 56 is in turn mounted upon sub-frame 58 for horizontaladjustment relative to sub-frame 58 by a threaded adjustment rod fixedto sub-frame 58 and coupled to end turn 56 by a pair of nuts 64.

Containers C are loaded upon chucks 42 of the burnoff machine by thetransfer machine of the aforementioned Banyas U.S. Pat. No. 3,590,982partially indicated at 66 in FIG. 1. The containers C, supported fromtheir moil portion M upon transfer machine 66 are lowered into chucks 42as the transfer machine and chucks move in synchronism to the left alongupper run 43 of the burn-off machine. Support of the containers istransferred from transfer machine-66 to the individual chucks 42 at theloading point designated L on FIG. 1. As described in greater detailbelow, the chucks 42 include three container gripping fingers which aremaintained in an open position until the container C is deposited bytransfer machine 66 onto chuck 42, at which time the chuck fingers areclosed by a closing mechanism schematically indicated at 68.

As the chucke 42 with their supported containers move to the left alongupper run 43 away from loading point L, the containers pass between apair of opposed elongate burners 70 which apply heat to the containeraround the region at which the moil portion is integrally joined to thecontainer. Burners 70 are sometimes referred to as pre-heat burnersalthough their function might be more accurately described as that ofmaintaining a controlled rate of cooling of the-finish region of thecontainer during its transit between loading point L and the location atwhich the moil is burned off. The containers, at the time they arereceived by the burn-off machine at loading point L are at a temperatureof between 900 and l000F and at the commencement of the actual burningoff of the In order to achieve even exposure of the container around itsentire circumference to the action of opposed burners 70, the containerchucks and their supported containers are driven in rotation by an upperspin cycle device schematically indicated at 72. As indicated in FIG. 1,burner 70 is continued around end turn 56 and terminates at the upstreamend of the main burn-off and finish forming burners 74. As the chucksenter the main burners 74, they are operatively engaged and again drivenin rotation by a second spin cycle mechanism schematically indicated'at76.

As the chucks 42 with the supported containers pass around end turn 56,the container is moved into an inverted position, with the moil portionwhich is to be burned off now being at the lower end of the container assupported on the chuck so that the moil portion can drop freely from thecontainer upon severance. Main burner 74 is constructed with a first orburn-off section of opposed burners which extend along the line oftravel of the finish portion of the container and directnarrowhigh-intensity flame jets, in a manner to be described in more detailbelow, at the line of desired severance. During its passage between themain burners, the container is continuously driven in rotation at acontrolled rate by spin cycle mechanism 76. The heat applied by theburners is adjusted so that severance of the moil portion from thecontainer will occur when the container is approximately one half of theway through main burners 74. During the latter half of its passagethrough main burner 74, the burners continue to apply heat to thesevered edge of the container and this heating action, combined with therotation of the container by spin cycle mechanism 76, acts to form abeaded finish on the container.

After the containers pass beyond main burners 74, they are conveyedthrough an inspection station 78 which -inspects the newly formed finishand is operable, by manipulation of the chuck 42, to causeejection of acontainer having a malformed finish.

After passing to the right beyond inspection station 78, chain 40 andthe supported chucks pass along a downwardly inclined portion 80 of thechain path to lower the inverted containers partially into containerreceiving pockets 82 of a schematically illustrated pocket conveyor 84driven in synchronism with chucks 42 of the burn-off machine. Chucks 42are constructed 8 a in a manner such that duringtheir passage alonginclined section 80, the containers are maintained in a verticalposition for free entry into pockets 82. A chuck opening mechanismschematically illustrated at 86 causes the chucks to open at the lowerend of inclined path section 80 to release the container to permit it tofreely drop the remaining distance into the aligned pocket 82 ofconveyor 84.

During its passage around the right-hand end turn 90 of its endlesspath, chain 40 passes into operative relationship with a chainlubricating mechanism designated generally 92 which is periodicallyactuated to lubricate the chain.

CHAIN DRIVE AND TENSIONING ADJUSTMENTS CHUCK ASSEMBLY Details of thechain and track construction, the chain drive and tensioningadjustments, and the chuck assembly are set forth in U.S. Pat. No.3,726,559, of which this application is a divisional application, andalso in a commonly owned copending divisional application ofU.S. Pat.No. 3,726,559 identified as Ser. No. 284,700, filed Aug. 30, 1972.

BURNER ASSEMBLY Details of the burner assembly are best shown in FIGS. 4through 8 inclusive.

Main burner 74 is constructed from a series of like burner modulesdesignated generally 280. In the plan view of FIG. 7, one completemodule is shown, with portions of two adjacent modules appearing at thetop and bottom of this Figure.

Each module 280 consists of two separate halves 282a and 282brespectively mounted on opposite sides of the path of movement of thecontainers C. The halves 282a and 282b'are identical and are mounted forindependent horizontal, vertical and pivotal adjustment relative to themachine frame F. A single set of reference numerals will be employed toidentify the parts of the two halves 282a and 282b.

Each module half includes a horizontally extending frame member284'having a housing 286 fixedly secured to each end. As best seen inFIG; 6, each housing 286 carries a pair of coaxially aligned plainbearings .288 which are slidably supported upon a transversely extendingtubular member 290 which is fixedly mounted upon the machine frame F. Asbest seen in FIG. 7, each module half is supported upon two tubu- 1plished by a pair of jacks 292 engaged between machine frame'F andmodule frame member 284.

v Returning to FIG. 6, each housing 286 supports a vertically extendingpost 294 fixedly securedto the housingA sleeve assembly 296 is slidablyreceived on each post 294 and carries a support bracket assembly 298. Anelongate pipe 300 is mounted in the two brackets 298 of each module halfand extends the entire length of the module. Elongate mounting bracketsof generally T-shaped cross-section 302 are fixedly secured, as bywelding, to each pipe 300. Each pipe 300 carries four individualbrackets 302, the brackets being spaced from each other to provideclearance at the points at which clamps 298 engage pipe 300 and also ata point approximately midway between clamps 298 for structure to bedescribed below.

Brackets 302 provide a mounting platform for a series of elongateindividual burner units designated generally 304, there being eightburner units supported in end-to-end relationship on each module half282a and 282b. Referring to FIG. 6, the burner units 304 are releasablyclamped upon bracket 302 by clamp assemblies designated generally 306,each of which includes a pivoted clamping finger 308 which is locked inthe clamping position shown in FIG. 15 by a knob 310 threadably receivedupon a clamping bolt 312. Pin 314 mounted in bracket 302 is engagedwithin grooves 316 7 in the bottom of each burner unit 304 to cooperatewith clamps 306 in locating the burner upon its bracket. Two pins 314and two clamping units 306 are I employed to mount each burner unit 304upon the brackets, one clamping unit and pin being located adjacent eachend of each burner unit. Due to the scale of FIG. 7, clamping units 306have been indicated only on one set of burner units 304 at the upper endof the module 280 as viewed in FIG. 7.

Vertical positioning of the burner units is accomplished by means of apair of jacks 318, a jack 318 being mounted upon each of housings 286and acting between the housing and the associated sleeve mounted supportbracket 298.

Pipe- 300 is supported in brackets 298 for rotation about the pipe axiswithin brackets 298. This enables an angular adjustment of burner units304 about the pipe axis by rotating the pipe within clamp assemblies298. Referring to FIG. 8, a clamp 320 is fixedly secured to pipe 300 ata location approximately midway between clamps 298. A jack 322 ismounted upon module frame member 284 and coupled by a pin and slotconnection designated generally 324' to a crank arm 326 fixedly securedto clamp 320. As indicated by the broken line showing of FIG. 8,actuation of jack 322 causes rotation of pipe 300 about its axis, thuspivoting the burner about the pipe axis. Because the burners on theopposed module halves 282a and 28217 are spaced from each other by adistance which provides only a small clearance for the passage ofcontainers C through the burners (see FIG. 6), pivotal adjustment of theburners usually requires a coordinated horizontal and verticaladjustment of the burner location by appropriate manipulation of jacks292 and 318.

Burner units 304 are of a laminated or built-up layer type ofconstruction, this construction being best shown in the cross-sectionalview of FIG. 4. The individual layers of the burner unit are formed fromappropriate lengths of bar or strip stock, each burner unit having atypical length of about one foot. The unit includes an upper housingmember 330, whose flat bottom surface 332 is formed with alongitudinally extending recess 334 which extends almost, but not quite,the entire length of housing 330, recess 334 terminating just short ofeach end of member 330. An inlet passage 336 extends from the rear wall338 of housing 330 to communicate at its inner end with a verticalpassage 340 which opens into recess 334. The outer end of passage 336 isformed with an internal screw thread as at 342 to receive a supplyconduit fitting.

A burner shim 344 is located in face-to-face engagement with the bottomsurface of housing member 330.

Shim 344 is the same length and width as is housing 330 and is formed,as best seen in FIG. 5, with a plurality of uniformly spaced parallelslots 346 which extend rearwardly from the forward edge 348 of the shim.As indicated in broken line in FIG. 5, recess 334 overlies the innerends of slots 346 so that the slots are in com munication with recess334 and thus, via passage 340, with inlet passage 336.

Shim 334, in turn, lies upon the top of an intermediate plate 350 havinga recess 352 formed in its top surface, recess 352 being of the sameoverall dimensions and vertically aligned with recess 334 of upperhousing member 330. The two recesses 334 and 352 cooperatively define acommon chamber split by shim 344, the

chamber having an inlet constituted by inlet passage 336 and passage 340and having a plurality of outlets constituted by slots 346.

A second shim plate 354 underlies intermediate plate 350, shim 354 beingof the same length as the other components of burner 70, but being of areduced width so that its forward edge 356 is spaced inwardly from theforward edge of the burner unit in approximate vertical alignment withthe inner ends of slots 346 of the burner shim.

Shim 354 is located on the top surface of a lower housing member 358which, like upper housing member 330, is constructed with an elongaterecess 360 of a configuration similar to that of recess 334. An inletpassage 362 extends forwardly from the rear wall of lower housing member358 to communicate with a vertical passage 364. An internal threadsection 366 at the read end of passage 362 is provided for theconnection of a supply fitting.

The various elements described above are clamped into assembledrelationship with each other as by a plurality of machine screws 368which pass through bores in upper housing member 330, shim 334, plate350, shim 354 and are threaded into tapped bores in lower housing member358.

In operation, a combustible gas under pressure is supplied to inletpassage 336, and passes through passage 340 into the chambercooperatively defined by recesses 334 and 352. The gas passes outwardlythrough slots 346 in the burner shim to establish a linear row of flamejets along the front edge of the burner unit, slots 346 constitutingflame ports or nozzles.

In the moil severing operation, it is desired to concentrate the appliedheat from the flame jets of burner units 304 to an extremely narrowband-like region of the container so that the line of severance ismaintained within close tolerances. Burner unit 304, by employing shim344 to establish the vertical dimension of the flame ports, enables theachievement of a linear row of accurately aligned, vertically narrowflame jets. Because shims 344 can be readily replaced, they also providefor great flexibility in modifying the operating characteristics of theburners by the employment of shims of different thicknesses, slotdimensions and/or slot spacings.

' For example, while the application of a very narrow band of heat tothe container during the moil severing operation for precisely locatingthe line of severance on the container may be desirable; during thesubsequent finish forming operation, it may be desirable to apply heatover a somewhat wider band, in which case a thicker shim 344 would beemployed. Further, the working temperatures of the glass containerduring the finish forming operation may not need to be as high as thedesired flame temperature during severing, in

which case different fuels might be employed as between the severing andfinish forming operations, together with different flame portconfigurations which can easily be established by varying the thicknessof the shims employed in the respective operations as to thickness, theslot dimensions and slot spacing.

During operation of the burner unit, air under pressure is supplied topassage 362 and discharged from the burner unit through the continuousslot 370 established between intermediate plate 350 and lower housing358 by shim 354. The air employed for this purpose is normally atambient temperature and establishes a 9 sharp thermal gradient in theglass during the severing operation, as well as exerting a coolingeffect on the burner unit.

SPIN CYCLE MECHANISM Details of the spin cycle mechanisms are disclosedin U. S. Pat. No. 3,726,559, of which the present application is adivisional application, and also in a commonly owned copendingdivisional application of U. S.

Pat. No. 3,726,559, identified as Ser. No. 284,700, filed Aug. 30,1972.'

CHAIN LUBRICATION SYSTEM We claim:

1. A burner assembly for establishing a linear row of flame jetscomprising an elongate upper housing member having a planar bottomsurface termianting at a longitudinally extending front edge, a lowerhousing member having a planar top surface coextensive with the bottomsurface of said upper member and terminating at a longitudinallyextending front edge, a shim plate coextensive with said planar surfacesand clampingly secured in face-to-face engagement therebetween, saidshim plate having a front edge coextensive with the respective frontedges of said upper and lower housing members and a plurality of slotsextending rearwardly from the front edge of said plate between saidhousing members, the planar surface of at least one of said membershaving an elongate recess extending in parallel rearwardly spacedrelationship to the front edge thereof to define an internal passagecommunicating with the slots in said shim plate, and means for supplyinga combustible gas under pressure to said recess.

2. A burner assembly as defined in claim 1 wherein said lower housingmember has a planar bottom surface extending parallel to its planarupper surface, a second shim plate mounted in face-to-face engagementwith said bottom surface of said lower member and having a front edgeextending parallel to and rearwardly spaced from the front edge of saidlower housing member, an elongate base member clampingly secured to thebottom of second shimplate and having a front edge aligned with thefront edge of said lower member, means defining an elongate recess inthe upper surface of said base member extending parallel to said frontedge of said base member in underlying relationship with the front edgeof said second shim plate, and means for supplying air under pressure tosaid recess.

1. A burner assembly for establishing a linear row of flame jetscomprising an elongate upper housing member having a planar bottomsurface termianting at a longitudinally extending front edge, a lowerhousing member having a planar top surface coextensive with the bottomsurface of said upper member and terminating at a longitudinallyextending front edge, a shim plate coextensive with said planar surfacesand clampingly secured in face-to-face engagement therebetween, saidshim plate having a front edge coextensive with the respective frontedges of said upper and lower housing members and a plurality of slotsextending rearwardly from the front edge of said plate between saidhousing members, the planar surface of at least one of said membershaving an elongate recess extending in parallel rearwardly spacedrelationship to the front edge thereof to define an internal passagecommunicating with the slots in said shim plate, and means for supplyinga combustible gas under pressure to said recess.
 2. A burner assembly asdefined in claim 1 wherein said lower housing member has a planar bottomsurface extending parallel to its planar upper surface, a second shimplate mounted in face-to-face engagement with said bottom surface ofsaid lower member and having a front edge extending parallel to andrearwardly spaced from the front edge of said lower housing member, anelongate base member clampingly secured to the bottom of second shimplate and having a front edge aligned with the front edge of said lowermember, means defining an elongate recess in the upper surface of saidbase member extending parallel to said front edge of said base member inunderlying relationship with the front edge of said second shim plate,and means for supplying air under pressure to said recess.